Bioactivity of the Terpenoids from Tripterygium mlfordii against Dendrolimus punctatus

Terpenoids were extracted from Tripterygium wilfordii Hook. The results of bioassay showed that the terpenoids had obvious insecticidal activities to Dendrolimus punctatus. The LC50 value of poisoning to the 3rd instarts of the pest insect was 1548. 50 mg/L. The value of median antifeeding dosage (AFD50) of the terpenoids against the 3rd larvae was 12. 25 ug/head. The median narcosis dosage (ND50) was 103. 98 ug/g. The terpenoids did not have contact poisoning to the insect. When the concentration of the terpenoids was between 10 mg/L and 10 000 mg/L, the mortality of the pupae was from 43. 3% to 63. 3%, the rate of unhatched eggs was 12. 0% to 84. 0%, and the rate of living larvae was 0. 0% to 95. 6%.